Flux coated electrode

ABSTRACT

An electrode for building up parts with an iron-base metal alloy. The electrode has a coating consisting essentially of 10 to 30 percent of calcium carbonate, 8 to 30 percent of fluor spar, 3 to 10 percent of titanium dioxide, 10 to 30 percent of ferromolybdenum, 1.0 to 8.0 of ferrocolumbium, 10 to 40 percent of ferrosilicon, 0 to 10 percent of metallic manganese, 0 to 10 percent of metallic chromium based on the total coating weight, the core of said electrode being chrome-nickel austenitic steel containing 17 to 21 percent of chromium, 7.5 to 11.0 percent of nickel, 0 to 5 percent of molybdenum, 0 to 1.3 percent of columbium, and 0 to 6 percent of manganese, the balance being iron.

United States Patent [191 Yarovinsky et al.

[ Nov. 19, 1974 FLUX COATED ELECTRODE Related US. Application Data [62] Division of Ser. No. 763,405, Sept. 27, 1968,

abandoned.

[52] US. Cl 117/205, 117/221, 252/520 [51] Int. Cl B23k 35/22, B23k 35/24 [58] Field of Search 117/205, 221; 252/520 [56] References Cited UNITED STATES PATENTS 2,142,045 12/1938 Chadwick ll7/206 2,632,835 3/1953 Wasserman 117/205 3,211,582 10/1965 Wasserman et a1 117/205 3,221,136 11/1965 Freeth 117/205 2/1966 Quaas 117/205 8/1970 Godai et al. 117/205 Primary Examiner-Leon D. Rosdol Assistant Examiner-Michael F. Esposito Attorney, Agent, or FirmWaters, Roditi, Schwartz &'

Nissen 5 7] ABSTRACT An electrode for building up parts with an iron-base metal alloy. The electrode has a coating consisting es- Sentially of 10 to 30 P nt q pa q ramrqatbqnatqt 8.

to 3 0 p ercent oifiuor spar, 3 to 10 percent of titanium dioxide, 10 to 30 percent of ferromolybdenum, 1.0 to 8.0 of ferrocolumbium, 10 to 40 percent of ferrosilicon, 0 to 10 percent of metallic manganese, 0 to 10 percent of metallic chromium based on the total coating weight, the core of said electrode being chromenickel austenitic steel containing 17 to 21 percent of chromium, 7.5 to 11.0 percent of nickel, 0 to 5 percent of molybdenum, 0 to 1.3 percent of columbium, and 0 to 6 percent of manganese, the balance being iron.

1 Claim, N0 Drawings FLUX COATED ELECTRODE This application is a division of our earlier application Ser. No. 763,405, filed Sept. 27, 1968 now abandoned.

The present invention relates to metal alloys, mainly for building up and manufacturing parts with surface exposed to friction when operating at a temperature up to 650C.

It is most expedient to use the present alloy in the field of power engineering and mechanical power enginern'ng for sealing surfaces of steam, stop and engineering fittings, and, additionally, in members of various designs, operating at a temperature up to 650C, where resistance to scratching is necessary.

Prior art alloys, used in the USSR and other countries, may be divided into two main groups.

Cobalt-base alloys (stellits). These alloys (Stellit-6, Real-96, Gal-0.5 Mo, etc.) are widely employed in many countries. They are used for building up sealing surfaces as cast rods being built up by acetylene and electric gas welding methods. All these alloys contain above 50 per cent of critical and expensive cobalt. Taking into consideration the property of cobalt to become more active under radioactive radiation, it is difficult to use building up for atomic power station fittings (of the first contour). Stellits are mainly used as cast rods. Their use for efficient electric-arc building up is hindered by the complexity of manufacturing electrodes (impracticability of mechanizing the manufacturing process, etc.). Stellits contain much carbon; this fact reduces the resistance to intercrystalline corrosion of stellit built up on structural and especially austenitic steels in the weakness zone, when they are used at a high temperature, which occurs because of the carbon difiusion from the built up stellit into the base metal.

In the USSR, besides cobalt-base stellit, at an earlier date there were developed and commercially used electrodes forming Cr-Ni-Si iron-base alloys, with the content of Si from 5 to 6 percent; Cr, 16 percent; Ni, 7 percent, the rest being Fe. However the main properties of said alloy (hardness at ordinary temperatures and especially at a high temperature up to 650C, the resistance to erosion and scratching, etc.) are considerably inferior to those of the cobalt stellit.

Manufacturing of electrodes for building up a Cr-Ni- Si alloy with a view to providing the desirable hardness range of the built-up metal involves difficulties in connection with the fact that the hardness of this metal is determined by the Si content, which element, under conditions of arc welding, is nonuniformly assimilated. With an increase of the Si content said alloy becomes brittle.

Thus, the main properties of this alloy are inferior to those of the cobalt-base alloys; that is why it is so difficult to achieve the desirable hardness value.

Although the Cr-Ni-Si iron-base alloy does not contain M0 or Cb, the application of these alloy additions is widely known.

The object of the present invention is to provide such a metal alloy which, without adding Co thereto, will possess properties not inferior to those of the cobaltbase alloy with respect to hardness, erosion and corrosion resistance, resistance to scratching and workabil- The above-mentioned and other objects are achieved by providing an iron-base alloy mainly for building up and manufacturing members, the surfaces of which are exposed to friction, when operating at a termperature up to 650C, the alloy, according to the invention, containing Cr, Ni, Si, Mn, Mo, Cb in the following proportions: l3.0-20.0 percent Cr,; 6.0l0.0 percent Ni; 4.0-6.0 percent Si; 20-60 percent Mn; 4.0-8.0 percent Mo; 0.5-2.0 percent Cb.

For building up the alloy onto parts, it is expedient to use an electrode, the coating of which contains: 10-30 percent of calcium carbonate, 8-30 percent of fluor spar, 3-10 percent of titanium dioxide, 10-30 percent of ferromolybdenum, 1.0-8.0 percent of ferrocolumbium, 10-40 percent of ferrosilicon, 0-10 percent of metallic manganese, 0-l0 percent of metallic chromium by the total weight of coating; the electrode core is made of Cr-Ni austenitic steel containing: 17-21 percent Cr; 7.5-1 1 percent Ni; 0-5 percent Mo; 0-1 .3 percent Cb; 0-6 percent Mg, the rest being Fe.

The present invention will become more fully apparent, from a consideration of the detailed description of the following examples of embodiments thereof.

The main requirement to be met by the built-up alloys is the provision of a stable and high hardness (38-50 HRC) at a room temperature resistance to scratching and preservation of sufficiently high values of hardness at elevated temperatures (e.g., about 30-36 HRC up to 600C). This was achieved by investigating the physical nature of strengthening of alloys and seeking methods of providing a stable range of alloy hardness. To this end, it was proposed to strengthen alloys by their combined alloying with elements, both reducing the parameters of the solid solution lattice and raising these parameters. As has been shown by experimental tests, this provided for a stable and high value of the alloy hardness. Simultaneously, the effect of the oxide film and influence of its composition, determined by the alloy composition on the resistance to scratching, strength and ductility of the'film was investigated. Adequate practice of alloying was also adopted while taking into account the abovementioned factors. Y

An iron-base alloy was thus developed, preferably intended for building up and manufacturing parts, the surfaces of which are exposed to friction when employed at a temperature up to 650C, the alloy containing, in addition to Fe: 13.0-20.0 percent Cr; 6.0-l0.0 percent Ni; 40-60 percent Si; 2.0-6.0 percent Mn; 4.0-8.0 Mo; 05-20 percent Cb.

For building up parts with the alloy, an electrode has been provided with a coating containing dry constituents: 10-30 percent of calcium carbonate; 8-30 percent of fluor spar; 3-10 percent of titanium dioxide; 10-30 percent of ferromolybdenum; 1.0-8 percent of ferrocolumbium; 10-40 percent of ferrosilicon; 0-10 percent of metallic manganese; 0-10 percent of metallic chromium in relation to the total coating weight. The electrode cores are made of Cr-Ni austenitic steel, containing: 17-21 percent Cr, -11 percent Ni, 0-5 percent Mo, 0.-l.3 percent Nb, 0-6 percent Mn, the rest being Fe.

The present invention is further illustrated by a detailed description of its exemplary embodiments.

Example 1 An alloy is prepared with: 14 percent Cr, 65 percent Ni, 4 percent Si, 2.5 percent Mn, 5 percent M0, 0.6 percent Cb, 0.1 percent C and up to 0.04 percent S and P, respectively.

An alloy of another composition is taken, containing: 16 percent Cr, 7.5 percent Ni, 4.8 percent Si, 4.0 percent Mn, 60 percent M0, 1.1 percent Cb, 0.12 percent C and up to 0.4 percent S and P, respectively.

An alloy of still another composition is prepared with: 18 percent Cr, 9 percent Ni, 5.5 percent Si, 5 percent Mn, 7 percent M0, 1.6 Cb, 0.18 percent C and up to 0.04 percent S and P, respectively.

The building up with each of the said alloys of the sealing surfaces of steam fittings, operating at a temperature of 600C, results in the built-up metal possessing the following properties: the coefficient of resistance to erosion, determined at a water flow rate equal to 150 m/sec is 1.16-1.25; hardness at a temperature of 20C, 38-50 HRC; at 600C, 30-36 HRC; the coefficient of friction at a specific pressure of 40 kg/sq.cm, 0.32.

Example 2 An electrode is prepared with a coating, containing: 21 percent of calcium carbonate; 14 percent of fluor spar; 7 percent of titanium dioxide; 21 percent of ferromolybdenum, 1.0 percent of ferrocolumbium; 22 percent of ferrosilicon; percent of metallic manganese, and 4 percent of metallic chromium.

An electrode core is made of austenitic steel, containing: percent Cr, 8.5 percent Ni, 1.0 percent Cb, 1.5 percent Mn.

Another electrode is prepared with a coating, containing: 24.5 percent of calcium carbonate, percent of fluor spar, 4 percent of titanium dioxide, 20 percent of ferromolybdenum; 6.5 percent of ferrocolumbium; 25 percent of ferrosilicon.

An electrode core is made of austenitic steel, containing: 21 percent Cr, 10 percent Ni, 6 percent Mn.

Said electrodes, when used for building up sealing surfaces of steam fittings operating at a temperature of up to 600C, provide built-up metal of the following chemical composition: 13-20 percent Cr, 6.0-10 percent Ni, 4.0-6.0 percent Si, 2.0-6.0 percent Mn, 4.0-8.0 percent Mo, 0.5-2.0 percent Ni, which possesses the same properties as the alloys of the abovementioned compositions.

Thus, the alloy proposed herein and the metal built up through use of the proposed electrode, possess the same and sometimes better properties than those of a cobalt-base stellit, e.g., the resistance to erosion in water current (the coefficient of stellit resistance to erosion being 1.08 and that of the proposed alloy 1.16-1.35); the proposed alloy has a higher resistance to scratching at a temperature up to 650C (when specific pressure is up to 800 kg/sq.cm; a high hardness value /at 20C, 38-50 HRC; at 650C. 26-30 HRC/; a low coefficient of friction lat 600C, 0.32, at 650C. 0.33-0.35), at a specific pressure equal to 20-70 kg/sq.cm as compared with 0.40-0.42 for cobalt stellit/; it also possesses resistance to corrosion in nitric, sulphuric, phosphoric and acetic acids as well as resistance to intercrystalline corrosion; and additionally, the production of the proposed alloy involves low costs in comparison with the making of cobalt stellit.

Though the present invention is described in connection with its preferred embodiment, it is evident that there may be variations and modifications that do not depart from the concept and scope of the invention, as those skilled in the art will easily understand.

These variations and modifications are considered as falling within the spirit and scope of the invention, as defined in the appended claims.

What is claimed is:

1. An electrode for building up parts whose surfaces are exposed to friction at temperatures of up to 650C with an iron-base alloy which will have a high hardness at this temperature and be scratch resistant, said electrode comprising a core, and a coating on said core which consists essentially of 10 to 30 percent of calcium carbonate, 8 to 30 percent of fluor spar, 3 to 10 percent of titanium dioxide, 10 to 30 percent of ferromolybdenum, 1.0 to 8.0 of ferrocolumbium, 10 to 40 percent of ferrosilicon, 0 to 10 percent of metallic manganese, and 0 to 10 percent of metallic chromium based on the total coating weight, said core consisting of chrome-nickel austenitic steel containing 17 to 21 percent of chromium, 7.5 to 1 1.0 percent of nickel, 0 to 5 percent of molybdenum, O to 1.3 percent of columbium, and 0 to 6 percent of manganese, the balance being iron. 

1. AN ELECTRODE FOR BUILDING UP PARTS WHOSE SURFACES ARE EXPOSED TO FRICTION AT TEMPERATURES OF UP TO 650*C WITH AN IRON-BASE ALLOY WHICH WILL HAVE A HIGH HARDNESS AT THIS TEMPERATURE AND BE SCRATCH RESISTANT, SAID ELECTRODE COMPRISING A CORE, AND A COATING ON SAID CORE WHICH CONSISTS ESSENTIALLY OF 10 TO 60 PERCENT OF CALCIUM CARBONATE, 8 TO 30 PERCENT OF FLUOR SPAR, 3 TO 10 PERCENT OF TITANIUM DIOXIDE, 10 TO 30 PERCENT OF FERROMOLYBDENUM, 1.0 TO 8.0 OF FERROCOLUMBIUM, 10 TO 40 PERCENT OF FERROSILICON, 0 TO 10 PERCENT OF METALLIC MANGANESE, AND 0 TO 10 PERCENT OF METALLIC CHROMIUM BASED ON THE TOTAL COATING WEIGHT, SAID CORE CONSISTING OF CHROME-NICKEL AUSTENITIC STEEL CONTAINING 17 TO 21 PERCENT OF CHROMIUM, 7.5 TO 11.0 PERCENT OF NICKEL, 0 TO 5 PERCENT OF MOLYBDENUM, 0 TO 1.3 PERCENT OF COLUMBIUM, AND 0 TO 6 PERCENT OF MANGANESE, THE BALANCE BEING IRON. 